Electronic mirrors developed for modern automobiles offer advantages over conventional optical or reflective glass based mirrors. Conventional electronic mirrors use a fixed field of view (FOV) for the camera subsystem capturing the rear view scene.
A conventional reflective-glass, rear-facing (or rear view) mirror is mounted on the front windshield in a position allowing a driver to easily change his/her gaze to view in a direction towards the rear of the vehicle. Conventional rear view mirrors have a relatively wide horizontal profile but relatively thin vertical profile. The thin vertical profile allows a driver to use the rear view mirror to see behind the vehicle while creating only a small obstruction when the driver is looking forward through the front windshield of the vehicle. If the cabin of the vehicle and rear window design do not create obstructions, a rear view mirror constructed to have a taller vertical size may offer more visibility behind the vehicle. However, a taller vertical size and/or placement obstructs the forward view of the driver attempting to look through the front windshield.
During the transition from installing traditional reflective mirrors, to installing electronic mirrors in vehicles, electronic mirrors will likely be similarly placed inside the cabin of the vehicle. A placement of the electronic mirror similar to the placement of a traditional reflective mirror will offer the driver a familiarity, which enhances safety. A similar placement also allows for the design of a secondary reflective mirror that may be used as a failsafe in the event the camera-display system of the electronic mirror fails.
Conventional commodity complementary metal-oxide semiconductor (CMOS) sensors are generally rectangular (or square) shaped to align with typical display aspect ratios. Sensor shapes for video display aspect ratios of 16:9 and 4:3 are common. Conventional reflective rear view mirrors and, subsequently, electronic rear view mirrors have a wider horizontal profile and thinner vertical profile than used in common image sensors. To reduce the cost of the electronic mirror subsystem, commodity image sensors are often used when designing electronic mirror subsystems. To comply with the rear view mirror aspect ratio, the full horizontal width of the sensor is utilized but only a cropped subsection of the vertical height of the sensor is actively displayed.
It would be desirable to implement an apparatus to adjust the field of view displayed on an electronic mirror using an automobile state or a driver position or action.
It would also be desirable to have a mechanism to make use of the hidden field of view of the sensor available on demand.
It would also be desirable to alter the field of view of the camera subsystem as a whole when more visibility is needed at the rear of vehicle (i.e., when backing up).